Sounding board for radio receiving sets and phonographs



1,633 944 J 1927' G. c. LINDSEY SOUNDING BOARD FOR RADIO RECEIVING SETS AND PHONOGRAPHS Filed April 23, 1925 2 sheets-sues: 1

- 1,633,944 June; 28 1927' G, c. LINDSEY SQUNDING BOARD FOR RADIO RECEIVING SETS AND PHONOGRAPHS Filed April 25, 1925 2 Sheets-Sheet 2 '10 phone or loud speaker,

Patented June 28, 1927.

UNITED STATES GEORGE C. LINDSEY, 01 LOS ANGELES, CALIFORNIA, ASSIGNOB PATENT OFFICE.

F SEVEN TEIRTY- SECONDS T0 MICHAEL GOZZO, ONE-EIGHTH 'IO DON EMINGER, SIX THIRTY-SEC- ONDS TO VICTOR Y. HENDB-ICK, AND NINE THIRTY-SECONDS T0 ROBERT TURNER.

SOUNDING BOARD FOR RADIO RECEIVING SETS AND PHONOGRAPHS.

Application filed April 23, 1925. Serial No. 25,269.-

Thls invention sounding boards vices.

Heretofore it has been customary in pho- 6 nographs and radio receiving sets to cause a diaphragm to be vibrated to produce the audible-sounds. These diaphragms are invariably small and formed of thin sheet material, such as .metal in the case of an ear or mica and similar materials in the case of a phonograph. It has been well recognized that by employing a diaphragm in sound producing or reproducing devices, the diaphragm produces a distortion of the sound vibrations, so that there is an effect of noise in conjunction with the tones produced by the diaphragm. I

An object of this invention is to employ a sounding board as a diaphragm and also as a sounding board in sound producing devices so that such distortion is eliminated.

With the foregoing and other objects in view which Wlll be made manifest in the following detailed description and s ecifically pointed out in the appended c aims,

reference is had to the accompanying drawings for an illustrative embodiment of the invention, wherein:

Figure 1 is a top plan view, parts being broken away and shown in section, illustrating a combined phonograph and radio receiving set to which my improved. sounding board has been applied,

section taken substan- Fig. 2 is a vertical tially on the line 2-2 of Fig. 1, showing being operated,

the phonograph as Fig. 3 1s a view similar to Fig).e2 showing the radio receiving set as ing employed, and Fig. 4 is a perspective view showing a modified form of sounding board.

Referring to the accompanying drawings wherein similar reference characters designate similar parts throughout. it will be understood that the phonograph and radio receiving set illustrated upon the drawings are employed for illustrative purposes only,

and that any suitable type of phonograph or radio receiving set or other device can be employed for mechanically transmitting sound vibrations to the sounding board of my improved construction. On.the drawings I have shown a container 10 which may grain wood, but it is -I preferably form in the be supported upon legs 11. A bracket 12 is mounted within the container, and a suitable link 13 is pivotally supported upon the bracket 12 and serves to pivotally suspend the sounding board of my improved construction so as to perm1t its free vibration.

My improved sounding board consists of a central'board 14 preferably. formed of good I possible to form the board out of other materials. Upon the sides of the board there are positioned two pieces of sheet material, indicated at 15 and 16 respectively. In the modifications shown in Figs. 1, 2 and 3, these pieces of material are tapered in form, and are somewhat curved. They have their converging edges constituting the top and bottom edges secured to the board 14 and their intermediate portions are disposed in spaced relation to the board. Only the converging edges are secured to the board so that the air pockets or-sound amplifying chambers 17 defined between the pieces of sheet material 15 and 16 and the board 14, are open at each end. board 14 opposite the pieces of sheet material 15 and 16" one or more F holes 18, as I find that best results are obtained :"by forming one or more apertures in the of sheet material.

The phonograph which I have shown upon the drawing consists ofa motor, generally designated at 19, which may be' of any conventional construction and which is adapted to rotate a plate 20 arranged upon the top of the container is shown as positioned upon the plate, and is engaged by a needle or stylus 22 which is mounted upon an arm 23. The arm 23 is rotatably mounted upon the upper end of a stem 24 which is fastened to the board 14 as by a suitable connection 25. It will .be noted that the position of the suspended link 13 is so arranged that the weight at the rear end of the board is sufiicient to cause the stylus 22to bear upon the top surface of the record 21. At the bottom of the board I have shown a needle 26 mounted on the board which is adapted to transmit sound vibrations from the unit 27 of a radio receiving set. In order to contact the needle 26 with the unit 27, the arm 23 is lifted and swung clear of the record 21 and the 10. A record 21- board 14 opposite the pieces loud s and theboard is vibrated plate 20, so that the board may be slightly lowered, bringing the needle 26 into contact with the radio unit 27 The operation of the device is as follows: If the phonograph is being operated, the sound vibrations which are produced upon the needle 22 by moving the record 21 beneath it are transmitted through the arm 23, the stem 24 and the connecting means 25 to the board 14. Because of the fact that the board 14 is freely suspended. these sound vibrations can freely influence the board, so as to vibrate it throughout its area and produce the sound. Although the board when influenced by the sound vibrations will produce an audible sound, this sound is not of a sufficient magnitude for ordinary purposes unless the board is of a considerable size. In order to reducethe size, I arrange the semi-confined air pockets near the board, which air pockets or sound amplifying chambers are formed material 15 and 16. B the sound is sufiicie'ntl small board can be sheet. material 15' and 16 define the air pockets 17 upon both sides of the board 14, and in this manner the vibration of the board 14 produces an audible sound because of the am lification produced by the air pockets. s previously stated, these air pockets are open at each end, so that the megaphone eifect of producing harsh sounds is eliminated. As illustrated in Figs. 1, 2

use of the air pockets and 3, the pieces of sheet material 15 and 16 are tapered, so as to tend to direct the sound produced in a given direction. namely, toward their large or widened end.

By this construction it will be appreciated that no arm 23 and that the board 14 serves not onl diaphragm, but as a sounding board: and in this manner the distort-ion of the sound waves is greatly eliminated. Furthermore, the orchestratlon of a pipe organ, a band or an orchestra, in'which a plurality of difl'erent notes are simultaneously produced, is perfectly reproduced by the sound- 1ng board 14 without-the distortion accompanied by the use of a diaphragm. When the radio receiving set is employed, It will be understood'that it is unnecessary to use a diaphra in the ear phones oraker device which may constitute the unit 27, but it is merely necessa to transfer or create mechanical sound vibraner as by the phono h.

In the modifications hown in Figs. 1, 2 and 3, the pieces of sheet material arepreferably formed of paper, although they may be formed of other material, such as veneer or a thin sheet of wood, if desired.

by the pieces of sheet.

y amplified so that a: used. The pieces of diaphragm is employed upon the sound vibrations to the stylus, and

In the modification improved sounding board consists of a central board 14 having twopieces of sheet material 15 and 16 secured upon its sides. These pieces of sheet material are shown as rectangular in form, having their top and bottom edgessecur'ed to the board 14 and having their center port-ions disposed" in spaced relation to the board, defining air pockets '17 upon both sides of the board. Suitable apertures or F holes 18 may be formed in the board 14, which are similar to the apertures or F holes 18 in the board shown in Figs. 1, 2 and 3. The pieces of sheet material 15 and 16 in the modification shown in Fig. 4 are preferably formed of a thin layer of wood, such as veneer, although they may be formed of other material, if so desired.

From'the above it will be appreciated that an improved construction in sound producingor reproducing devices is provided, which eliminates the use of a diaphragm and consequently the distortion produced by the diaphragm, so that a clear and undistorted tone or a plurality of tones is produced by the device.

It will be understood that various changes in the detail of construction may be made without departing from the spirit or scope of the invention as defined by the appended claims.

I claim:

1. A device of the character described comprising a support, a sounding board of wood freely suspended from the support for vibration throughout its area at audible frequency, a stylus mounted on the support and engaging the sounding board for vibrating the latter, means for reproducing and transmittin sound. vibrations to the'stylus, and tapered sheet material upon the side of the board with its medial portion s aced from the board to form a sound amplig'ing chamber, the converging sides of the sheet material being fixed to the board with the ends of the sheet material spaced from the board to form open ends for the sound amplifying chamber, and there bein an aperture in the ggard opposite the sound amplifying cham- 2. A device of the character described comprising a support, a sounding board freely su ended from the support for vibration th gighout its area, a stylus mounted independently ofthe board and engaging the board for vibrating it at audible equency, means for reproducing and transmitting sheet material u n the side of the board with edges of the s eet material fixed to the board and the medial portion of the. sheet material p g chamber- '3. i devioe of the character described comshown in Fig. 4, the

s aced from the board to form a sound am- I prising a support, a sounding board freely suspended from the support for vibration throughout its area at audible frequency, a'

4. A device of the character described comprising a support, a sounding board freely suspended from the support for. vibration throughout its area at audiblefrequency, a stylus engaging the board for vibrating the same, means for reproducing and transmitting sound vibration to the stylus, and means mounted on the side of the board defining a sound amplifying chamber at the side of the board.

5. A device of the characterdescribed com prising a support, a sounding board freely suspended from the support for vibration throughout its area at audible frequency; a stylus for vibrating the board, means for reproducin and transmitting sound vibrations to the sty us, and means mounted on the side of the board defining a sound amplifying chamber at the side of the board, there being an aperture in the board opposite the sound amplifying chamber.

6. A device of the character described comprising a support, a sounding board freely suspended from the support for vibration throughout its area at audible frequency, a stylus for vibrating the board, means for'reproducing and transmittin sound vibrations to the stylus, and tapered s eet material upon the side of the board with its converging sides fixed to the board and its medial por tion spaced from the board to form a sound amplifying chamber.

In testimony whereof I have-signed my name to this specification.

GEORGE o. LINDSEY. 

